I've seen images with it, he resolution is so much better than any competition. I had a Samyang 14mm "coke bottle", it was the worst lens I've ever owned. I sent it right back.
The Nikon 14-24 is sharp in lab tests, but in the field, in bright sun, its difficult to avoid flare that either ruins the image entirely, or degrades contrast. Its a cloudy day lens. I haven't seen reports of flare for the Zeiss.